Murata only offers ultrasonic sensors designed to be used with air as the medium, not water or solids. Four varieties of ultrasonic sensors are available: open structure type, drip-proof type, high-frequency type, and SMD type. Each type has its own features, with some being suitable only for specific applications. For details, refer to the lineup page for each type.
In addition, the sensors contain no circuitry. Either create your own circuits, referring to the basic reference circuit diagrams on the website, or obtain suitable circuits from a manufacturer of IC devices.
On the website you will find basic knowledge about the characteristics, etc., of ultrasonic waves, application examples, lists of unsuitable applications, more detailed precautions, frequently asked questions, and more. Please feel free to make use of these resources.